Method for the manufacturing of an absorbent structure and an absorbent article

ABSTRACT

A method for the manufacturing of an absorbent structure in an absorbent article, such as a sanitary napkin, tampon, panty protector, wound or sore dressing and like articles is produced by using absorbent material in roll form directly in the product without first defibrating the material and then forming a mat. The material possesses good dispersion properties and swelling properties, which are meaningful to the function of the product. A high surface dryness is obtained, among other things. In addition to cellulose fibers, the absorbent structure may also include superabsorbent material and/or binding fibers, among other ingredients. The pulp mat is very thin, therewith obviating the need to compress the mat further in the product. In the case of certain product applications, the material is softened mechanically prior to its use as an absorbent material.

BACKGROUND

1. Field of the Invention

The present invention relates to a method for manufacturing an absorbentstructure in an absorbent article, such as a sanitary napkin, a tampon,a panty protector, an incontinence guard, a diaper, a wound or soredressing, a saliva absorbent and like articles. The invention alsorelates to an article manufactured according to the method.

2. Discussion of Related Art

Many different types of absorbent articles of this kind are known to theart. The absorbent bodies of such articles are typically produced bydry-defibering and fluffing cellulose pulp in roll, bale or sheet formfor instance, to form a pulp mat, sometimes admixed with so-calledsuperabsorbent material in the pulp mat, these absorbents being polymerswhich are capable of absorbing many times their own weight of water orbody fluid.

The pulp body is often compressed so as to enhance its fluid-wickingability and also in order to reduce pulp body bulk and therewith obtainan article which is as compact as possible.

The absorbent body may also include other constituents, for instanceconstituents which will improve its fluid-aquisition properties or itsfluid-retaining properties, or which will increase its coherentstrength, i.e. its coherency, and its ability to withstand deformationin use.

One serious drawback with products of this nature is found in the totalabsorption capacity of the articles and also in the fact that thearticles will often leak long before their total absorption capacity hasbeen fully utilized. Among other things, this is because the body fluiddischarged by the wearer is unable to penetrate into the absorptionmaterial and to spread to hitherto unused areas of the article quicklyenough, but instead leaks from the sides of the sanitary napkin, thediaper or the incontinence guard. The ability of the materials used inthe article to disperse the absorbed fluid throughout the entireabsorbent body and to retain said fluid in the absorption body is thushighly important.

Another problem resides in so-called rewetting, i.e. the transference ofbody fluid that has already been absorbed back into contact with thewearer's skin as a result of external forces, for instance when thewearer sits down. It is generally desired that the surface of thearticle that lies proximal to the wearer in use will remain as dry aspossible.

Another desideratum with regard to the majority of hygiene products isthat the article shall be thin, so that it can be worn as discretely aspossible.

A very large part of the production plants used in the manufacture ofthe aforesaid hygiene articles is comprised of defibrating equipment,pneumatic conveying systems and mat-forming equipment. This equipment isalso the source of serious faults in the production plants. Equipmentfor compressing the finished pulp mat or the finished hygiene product isfurthermore often included downstream of the production plants.

A separate problem is related to the use of superabsorbent material inabsorbent articles. The superabsorbent material is normally available inthe form of granules, which are difficult to bind to the absorbentstructure especially if the percentage of superabsorbent is high, i e50% and higher calculated on the total weight of the absorbent structurein a dry state.

It is known from International Patent Application WO 90/05808 to producea pulp web by dry-forming, which is later defibered, so-calleddry-formed roll or reel pulp. Flash-dried paper-pulp fibres, which mayconsist of thermomechanical pulp, chemi-thermomechanical pulp, CTMP, orchemical paper pulp, sulphite or sulphate pulp with a dry solids contentof about 80% is delivered by means of an air stream in a controlled flowto a forming head arranged above a forming wire and there formed into aweb that has a weight per unit area of 300-1500 g/m² and a density of550-1000 kg/m³. Air is sucked away through a suction box placed beneaththe wire. The moisture content in the process shall be 5-30%.

The web is pre-pressed to a density of 550-1000 kg/m³ in order toslightly reduce the bulk of the web prior to the final pressing stage.The pressed web has a mechanical strength which enables the web to berolled-up or handled in sheet form for storage and transportationpurposes. The web can be readily defibered and is intended to beconverted into fluff for use in the manufacture of absorbent bodies orpads for diapers, sanitary napkins and like articles.

Another method for the manufacturing of an absorbent structure isdescribed in European Patent 0 122 042, where a mixture of hydrophilicfibres and water insoluble particles of insoluble hydrogel is airlaidinto a web and compressed to a density of 0.15 to about 1.0 g/cm3. Thismethod however comprises several production steps, where the dry lapbase material is first disintegrated into cellulose fibres by use of ahammer mill, whereafter the fibres are deposited on a screen surface andformed to the absorbent structure, which is then compressed. Thesemanufacturing steps make this process rather complicated and expensive.

SUMMARY AND OBJECTS

An object of the present invention is to provide in an absorbent articleof the aforedescribed kind an absorbent structure which exhibitsextremely good absorption properties, especially with respect to itsability to spread fluid and also with respect to its ability to retainsaid fluid within the material. The material will preferably exhibit lowrewetting tendencies as well as being capable of being made very thin.It is also desired to provide a simplified method of manufacturingabsorbent articles of the kind defined in the introduction. Theseobjects and desiderata are achieved with a manufacturing method in whichparticulate material comprising 30-100%, preferably at least 50% andmost preferably at least 70% flash-dried cellulose fibres is dry-formedto a web with a weight per unit area of between 100-2000 g/m2 andcompressed to a density of between 0.3-1.0 g/cm3 and that the webwithout subsequent defibration and fluffing is incorporated as anabsorbent structure in an absorbent article.

Non-defibered, dry-formed roll pulp has been found to be an extremelygood absorption material and can be used directly as an absorbentmaterial in hygiene articles, without being defibered. The material alsohas good fluid wicking properties and swelling properties, which aremeaningful to the function of the product. The pulp mat is very thin andtherefore need not be further compressed in the product or article.

In the case of certain product applications in hygiene articles, it isconvenient to soften dry-formed roll pulp prior to its use as anabsorption material. The earlier mentioned good absorption properties,fluid wicking properties and swelling properties are not influenced bythe softening process to any great extent. One method to soften anabsorbent sheet is described in European Patent Application EP 0 360472, where the compressed absorbent material is worked between partiallycutting rollers and thereby gaining softness. This method however leadsamong other things to decreased strength in the softened material.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described in more detail with reference to anumber of exemplifying embodiments thereof and also with reference tothe accompanying drawings, in which:

FIG. 1 illustrates the absorption properties of a dry-formedCTMP-material subsequent to being worked between rolls at different rollspacings. Conventionally formed and compressed pulp mats of CTMP-pulpand chemical pulp respectively were used as references.

FIG. 2 illustrates the absorption properties of a dry-formedCTMP-material subsequent to being softened. Conventionally formed andcompressed mats comprised of CTMP-pulp and chemical pulp respectivelywere used as references.

FIG. 3 illustrates the absorption properties of a complete absorbentarticle manufactured with dry-formed CTMP in the core. Conventionallymanufactured products of corresponding compositions were used asreferences.

FIG. 4 illustrates the fluid aquisition time of a complete absorbentarticle produced with dry-formed CTMP in the core. Conventionallymanufactured products of corresponding compositions were used asreferences.

FIG. 5 illustrates the degree of utilization of a complete absorbentarticle produced with dry-formed CTMP in the core. Conventionallymanufactured products of corresponding compositions were used asreferences.

FIG. 6 illustrates the absorption properties of an absorbent structureproduced with dry-formed CTMP, both with and without a superabsorbentadmixture. Conventionally manufactured pulp cores both with and withouta superabsorbent admixture were used as references.

FIG. 7 illustrates rewetting of a complete absorbent article producedwith dry-formed CTMP in the core. Conventionally manufactured productsof corresponding compositions were used as references.

FIG. 8 illustrates the respective rewetting of an unsoftened and asoftened absorbent structure in connection with blood absorption whichwas produced with dry-formed CTMP in the core, both with and with-out asuperabsorbent admixture.

FIG. 9 illustrates rewetting of a completely absorbent article inconnection with blood absorption which was produced from dry-formed CTMPin the core. Conventionally manufactured products of correspondingcomposition were used as references.

FIGS. 10-11 illustrate schematically the composition of variousexemplifying embodiments of inventive absorbent articles.

FIG. 12 illustrates the structure of a cross section of the material inunsoftened condition.

FIG. 13 illustrates the structure of a cross section of the material insoftened condition.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Important properties of a material used in the manufacture of a hygienearticle are its absorbent capacity, absorption rate, wicking capacity,drainage capacity, retention capacity, rewetting, softness andsmoothness.

The fluids concerned are urine, menstruation blood, blood, fluid matterfrom wounds and sores, rinsing fluid and saliva.

An object of the present invention is to provide in an absorbent articlesuch as a sanitary napkin, tampon, panty protector, incontinence guard,diaper, bed protector, wound or sore dressing, saliva absorbent and likearticles, an absorbent structure which exhibits highly effectiveabsorption properties, especially with regard to its fluid-wicking rateand its ability to retain fluid throughout the material. The materialwill also preferably have low rewetting and be capable of being madevery thin and smooth. It is also desired to simplify the manufacturingprocess. A finished absorbent material in roll form which can be usedwithout needing to be defibered would partially reduce the need for theearlier mentioned defibering equipment, pneumatic conveying systems andmat-forming equipment, and consequently there is a demand for suchmaterial.

The aforesaid objects and desiderata have been achieved in accordancewith the invention by using a manufacturing method in which particulatematerial comprising 30-100%, preferably at least 50% and most preferablyat least 70% flash-dried cellulose fibres is dry-formed to a web with aweight per unit area of between 100-2000 g/m2 and compressed to adensity of between 0.3-1.0 g/cm3 and that the web without subsequentdefibration and fluffing is incorporated as an absorbent structure in anabsorbent article.

In accordance with the invention, there is used a dry-formed productwhich is manufactured from particulate material as mechanical pulp orchemi-thermomechanical pulp (CTMP) or a corresponding productmanufactured from sulphite pulp or sulphate pulp, so-called chemicalcellulose pulp. Cellulose fibres which have been stiffened chemicallymay also be used. In the dry-formed product can also be included otherparticulate matter as superabsorbents, thermoplastic binding fibres andother kind of fibres.

Non-treated dry-formed roll pulp has extremely good absorption, wickingand swelling properties, and it has been found possible to use thematerial immediately as an absorption material in hygiene articleswithout defibrating the pulp. In the case of certain absorbent articles,it has been found suitable to soften the material slightly prior to itsuse. One method of softening the material is described below.

Dry-formed roll pulp has a good integrity which means that in the caseof use of superabsorbent materials in dry-formed roll pulp the granuleswill be well bound to the absorbent structure and will not spread duringfurther conversion into absorbent hygiene products.

Dry-formed cellulose pulp can be produced, for instance, by forming aweb of flash-dried paper pulp fibres in accordance with the methoddescribed in International Patent Application WO 90/05808.

Cellulose pulp fibres have a so-called curl value which defines thecrookedness of the fibre. Curl value can be measured according to themethod described by B. D. Jordan, N. G. Nguyen in Papper och Tra 4/1986,page 313. An embodiment of the present invention has a curl-value ofbetween 0.20 and 0.40.

Softening of the Material

The material can be given a softness which renders the material highlysuitable for use as an absorption material in the majority of hygienearticles, by working dry-formed roll pulp between for instancecorrugated rolls. The material can be brought to different degrees ofsoftness for different product applications, by working the materialbetween different types of rolls and at different roll spacings.

Dry-formed roll pulp which has been softened in this way exhibits verygood product properties, and the earlier mentioned good absorptionproperties are not influenced by the softening process to any greatextent.

The material is delaminated in the softening process as illustrated inFIGS. 12 and 13. The unsoftened material has normally an even highdensity throughout the whole the thickness of the material (61). As aresult of the softening process the material is delaminated so as toform a plurality of partially separated (63), thin fibre layers (62).Softening and delamination of the material reduces its total density tosome extent, although the original density is essentially retained ineach individual layer. Because a very high density is retained in theindividual layers, the good fluid wicking properties of the material areretained despite the increase in bulk obtained in conjunction with thesoftening process. The total bulk is increased by up to 300%, normally1-100%, as a result of the softening process, depending on the methodused and the extent to which the material is softened.

It will be understood that the aforesaid material softening method hasbeen given solely by way of example and that corresponding results canbe achieved with the aid of other methods. For instance, the materialcould eventually be softened by means of ultrasonic energy, microwaves,by moisturizing the material, or with the aid of chemical additives.

Investigation of Material Properties

The test equipment described below was used to evaluate absorptionproperties.

Method 1. Absorption Properties Up an Inclined Plane

A rectangular test body was punched from the material and a line wasdrawn transversely across the test body at a point 11 cm from one shortend of the body. A fluid container was placed adjacent laboratory scalesand both the scales and the container were adjusted to a horizontalposition. A plexiglass plate was placed on the scales at a 30° slope,with one free edge of the plate extending slightly down into thecontainer. A line had been drawn transversely across the plate at apoint 11 cm from the lower edge of said plate. Test fluid (0.9%NaCl-solution) was poured into the container, until 20 mm of theplexiglass plate was located beneath the surface of the fluid. The testbody was secured on the plexiglass plate so that the line drawn on thetest body coincided with the line drawn on the plate while, at the sametime, folding away the lower part of the test body so as to prevent itfrom coming into contact with the test liquid. A clock was started atthe same time as the test body was laid onto the plate, with the testbody extended down into the solution to the same extent as the plate.The increase in weight of the test body with time was recorded.

Method 2. Measurements of Absorption Capacity and Degree of Utilization

A test product was secured in a fixture. Test fluid (0.9% NaCl-solution)was delivered to the wetting point of the product over a period of 60minutes at the rate at which the fluid was absorbed. The amount of fluidabsorbed was measured continuously and the total amount of fluidabsorbed by the product constitutes the utilized absorption capacity ofthe test product. The test product was then placed in a fluid bath, inwhich it had the maximum opportunity of absorbing test fluid. The testproduct was then again weighed and the total absorption capacitycalculated. The degree of utilization is given by the quotient betweenthe utilized absorption capacity of the test product and the totalabsorption capacity.

Method 3. Measurements of Rewetting, Fluid Wicking and Aquisition Time

Four batches of sample fluid (0.9% NaCl-solution), each comprising 28ml, were delivered at 20-minute intervals. The time measurement wascontinued until all fluid had been absorbed. The extent to which thefluid had dispersed in the diaper was noted after each batch. Subsequentto delivering the last batch of fluid, filter paper was placed over thewetting point and loaded with a weight of 1.1 kg for 15 seconds. Thefilter paper was weighed both before and after applying the load andrewetting was recorded.

Method 4. Determining Rewetting Measurements

A diaper intended for a given weight range was weighed and then placedon a flat support surface. An adapted quantity of test fluid (0.9%NaCl-solution, 100 ml for a diaper intended for a weight range of 7-15kg) was delivered to the wetting point of the diaper. A further 100 mlof fluid was delivered after 20 minutes. When all fluid had beenabsorbed, a filter paper was placed over the wetting point and loadedwith a weight of 1.1 kg for 15 seconds. The filter paper was weighedboth before and after applying the load and the result was recorded as afirst rewetting instance. After a further 20 minutes, another 100 ml offluid was delivered and when all fluid had been absorbed, the procedurewas repeated with a fresh filter paper and the result recorded as asecond rewetting instance.

Method 5. Determining Blood Absorption

A test body, 65×200 mm, was punched from the material. 5 ml test fluid(0.9% NaCl-solution) were delivered to the wetting point on the testbody. Dispersion of the fluid was measured after about 30 minutes. Afurther 5 ml of test fluid (0.9% NaCl-solution) were then delivered tothe wetting point and fluid dispersion was measured after about afurther 30 minutes. Subsequent to the last delivery, eight filter paperswere placed over the wetting point and loaded with a weight of 4.875 kgfor 15 seconds. The filter papers were weighed both before and afterapplying the load and rewetting was recorded.

Test Results

Softening

With the intention of investigating how the material was affected atdifferent softening roll spacings when softening the material, amaterial was tested under different softening conditions. For instance,in the case of a dry-formed CTMP-material having a weight per unit areaof 900 g/m² and a density of 0.63 g/cm³, a suitable roll spacing is1.7-2.4 mm during the softening process. The material is not influencedto any great extent at roll spacings which lie within this range. FIG. 1illustrates the absorption properties at different roll spacings. Theresults were determined in accordance with Method 1.

A Material according to the invention, roll spacing 1.7 mm.

B Material according to the invention, roll spacing 2.0 mm.

C Material according to the invention, roll spacing 2.4 mm.

D Material according to the invention, roll spacing 2.0 mm, softenedtwice.

E Material according to the invention, roll spacing 2.0 mm, softenedfour times.

F CTMP-pulp, density 0.125 g/cm³.

G Chemical sulphate pulp, density 0.125 g/cm³.

Absorption Properties of Absorbent Structures

The absorption properties of an inventive CTMP-material having a weightper unit area of 900 g/m² and a density of 0.63 g/cm³ compared withthose of corresponding pulp cores produced from conventionally defibredand web-formed CTMP and corresponding chemical pulp are shown in FIG. 2.In the absence of superabsorbent material, the absorption capacity isabout 9 g of fluid for each gram of absorbent material. The results weredetermined in accordance with Method 1.

A Material according to the invention.

B CTMP-pulp, density 0.125 g/cm³.

C Chemical sulphate pulp, density 0.125 g/cm³.

Product Properties of a Complete Absorbent Article

With the intention of studying other properties of complete absorbentarticles, test products were prepared in the form of conventionalchildren's diapers which comprised a T-shaped absorbent body (T-core),which lies nearest the wearer, and a rectangular absorbent body (R-core)which lies beneath the T-core, where the rectangular absorbent body inthe test products was produced from an inventive CTMP-material. In theconventional products, the T-shaped absorbent body (T-core) and therectangular absorbent body (R-core) were comprised of conventionaldefibred CTMP and chemical pulp.

Measurements of the Absorption Capacity

Products which comprised an inventive CTMP-material exhibited anabsorption in grams which was equivalent to the reference products whichhad corresponding pulp cores that were comprised of conventionallydefibred and mat-formed CTMP and chemical pulp. The results are setforth in FIG. 3. The results were determined in accordance with Method2.

A Reference diaper Libero Girl.

B Reference diaper Libero Boy.

C Child diaper comprising inventive material.

Measurements of Fluid Aquisition Time

Products in which the R-core comprised an inventive CTMP-materialexhibited a shorter fluid aquisition time than the reference product.This implies that an R-core which contains inventive CTMP-material isable to drain the T-core more effectively. The results can be seen fromFIG. 4. The results were determined in accordance with Method 3.

A Reference diaper Libero Girl.

B Reference diaper Libero Boy.

C Child diaper comprising inventive material.

Measurements of the Utilization of the Absorbent Body

A comparison between the degree of utilization of the absorbent body inan absorbent article which contained an inventive CTMP-material and acorresponding absorbent article which contained conventional CTMP andchemical pulp showed that the degree of utilization is about the same,although slightly on the plus side for an inventive CTMP-material. Theresults can be seen from FIG. 5. The results were determined inaccordance with Method 2.

A Reference diaper Libero Girl.

B Reference diaper Libero Boy.

C Child diaper comprising inventive material.

Admixing Superabsorbent Material

The presence of superabsorbent material in an absorbent body willinfluence the absorption properties of the body. Superabsorbent materialcan be incorporated in the absorbent body in different ways. Forinstance it may be admixed with the body material, laid in layers in thebody, or disposed therein in some other way. This admixture ofsuperabsorbent material can be effected in conjunction withmanufacturing the dry-formed material, although it may also be effectedduring some other part of the manufacturing process. The absorptionproperties were compared with an inventive CTMP-material to which nosuperabsorbent material had been added and also with corresponding pulpcores comprised of conventional defibred CTMP and chemical pulp. Theresults of this comparison are shown in FIG. 6. The results weredetermined in accordance with Method 1.

A Chemical sulphate pulp containing 30% superabsorbent and having adensity of 0.125 g/cm³.

B Inventive material containing 30% superabsorbent.

C Reference diaper containing 30% superabsorbent.

D Inventive material containing no superabsorbent.

Rewetting Measurements

Products which comprised an inventive CTMP-material in the R-coreexhibited better rewetting values than the reference product. This alsoimplies that an R-core which contains inventive CTMP-material is able todrain the T-core more effectively. The results can be seen from FIG. 7.The results were determined in accordance with Method 4.

A Reference diaper Libero Girl.

B Reference diaper Libero Boy.

C Child diaper comprising inventive material.

Rewetting Measurements, Specific for Blood Absorption

In the case of blood absorption, products which comprised an inventivesoftened CTMP-material showed better rewetting values than non-softenedproducts. The results also showed that when absorbing blood, productswhich lacked superabsorbent material exhibited lower rewetting valuesthan material which contained superabsorbent material. Material whichlacks superabsorbent material also disperses blood much moreeffectively. The results can be seen from FIGS. 8 and 9. The referenceproducts comprised two different products frequently found on themarket. The results were determined in accordance with Method 5. Theprerequisites for this effect are that at least one layer of the pulpmat is free from superabsorbent material. Of course, this does notexclude the presence of such material in other parts of the absorbentarticle.

FIG. 8

A Inventive material 350 g/m2.

B Inventive material 350 g/m2, softened.

C Inventive material 350 g/m2+5% superabsorbent.

D Inventive material 350 g/m2+5% superabsorbent, softened.

FIG. 9

A Reference product 1.

B Reference product 2.

C Product containing inventive material.

Network Strength

Dry-formed roll pulp will normally have sufficient mat strength for theproduct applications intended here. If the network strength of certainproduct applications should be found insufficient, the network strengthcan be increased by reinforcing the structure in some suitable manner,by adding reinforcing fibres, binding fibres or binding agent to thecellulose fibre mixture. The network strength can also be increased byincorporating a reinforcing layer of, for instance, plastic, non-woven,net or threads in the absorbent structure, or by fastening a reinforcinglayer or an outer sheet on one or both sides of the material.

Density and Surface Weight

The softened pulp mat is still very thin, and consequently it isunnecessary in many cases to further compress the mat prior to its usein an absorbent article. A suitable density is 0.3-1.0 g/cm³, preferably0.4-0.9 g/cm³ and most preferably 0.5-0.85 g/cm³. A suitable weight perunit area is between 100-2000 g/m², preferably 150-1500 g/m² and mostpreferably 200-1000 g/cm². When calculating the density, the thicknessof the material was measured with the aid of a Mitutoyo thickness meter.

Description of a First Exemplifying Embodiment

FIG. 10 illustrates a diaper constructed in accordance with oneembodiment of the invention. The diaper includes, in a conventionalmanner, an absorbent body 11 which is enclosed between a fluid-permeabletop sheet 12, which conveniently comprises a soft non-woven material, aperforated plastic film or the like and which is intended to lieproximal to the wearer in use, and a fluid-impermeable bottom sheet 13.The sheets 12 and 13 have parts which extend beyond the absorbent body11 and the sheets are joined together at these protruding parts. Thebottom sheet 13 is comprised of a suitable plastic material, forinstance polyethylene. It will be understood, however, that other knownmaterials can be used for the top and bottom sheets, within the scope ofthe invention.

The absorbent body is comprised of two or more layers, an upper fluidaquisition layer 14 and one or two lower wicking layers and storagelayers 15 and 16. The inventive material is used either as a wickinglayer 15 or a storage layer 16 or as both these layers. Those layers inwhich inventive material is not used may be comprised of other typesmaterials, for instance conventional cellulose fibre material.

The purpose of the aquisition layer 14 is to rapidly take-up a givenquantity of fluid. This fluid shall solely be held loosely in the fibrestructure and quickly drained therefrom. The aquisition layer 14 has arelatively open fibre structure of relatively low density and contains0-10% superabsorbent material. The superabsorbent material used in theaquisition layer 14 will preferably have a high gel strength, so that anopen three-dimensional fibre structure will be retained in this layerafter becoming wet.

The main purpose of the wicking layer 15 is to transport the fluidreceived in the aquisition layer 14 effectively to the storage layer 16located beneath the wicking layer 15 and to ensure that the greatestpossible part of the storage layer 16 is utilized for absorptionpurposes. The wicking layer 15 therefore has a relatively lowsuperabsorbent content. A suitable superabsorbent content in the case ofthe wicking layer 15 is 0-20%, while a suitable density range is 0.3-1.0g/cm3. A suitable weight per unit area range in the case of the wickinglayer 15 is 50-1500 g/m2.

The purpose of the storage layer 16 is to absorb and retain the fluidwhich is dispersed to the storage layer 16 through the wicking layer 15.The storage layer 16 may therefore have a relatively high superabsorbentcontent and a relatively high density. Suitable density values are0.4-1.0 g/cm3, while a suitable superabsorbent content is 30-70%. Asuitable weight per unit area range in the case of the storage layer 16is 100-1500 g/m2.

The wicking layer 15 and the storage layer 16 may optionally be combinedto form a single layer. In this case, the single layer will have arelatively high superabsorbent content and a relatively high density.Suitable density values are 0.3-1.0 g/cm3, while a suitablesuperabsorbent content is 20-70%. A suitable weight per unit area rangein the case of a combined wicking and storage layer is 150-2000 g/m2.

When the wicking layer 15 and the storage layer 16 are combined in asingle layer, the superabsorbent content of the layer can be variedthroughout the product, so as to obtain a superabsorbent gradient in thedepth, length and/or the breadth direction of the product.

The various layers may have different forms and sizes. Normally, theabsorbent structure is combined with some form of elastication, interalia in the crotch region of the product, in order to improve productefficiency.

Destination of a Second Exemplifying Embodiment

FIG. 11 illustrates an exemplifying embodiment of an inventive salivaabsorbent. The saliva absorbent includes, in a conventional manner, anabsorbent body 51 which is enclosed between a fluid-permeable top sheet52, which is suitably comprised of a perforated plastic film or likematerial and which is intended to lie proximal to the wearer when used,and a fluid-impermeable bottom sheet 53. The bottom sheet 53 iscomprised of a suitable plastic material, for instance polyethylene. Itwill be understood, however, that the top sheet 52 and the bottom sheet53 may be comprised of other known materials within the scope of theinvention.

The absorbent body 51 is comprised solely of one single layer. Thislayer may be comprised of inventive dry-formed material and has arelatively high density and a superabsorbent content of 20-80%. Asuitable density range in respect of the absorbent body 51 is 0.4-0.8g/cm3.

It will be understood that the invention is not restricted to theillustrated and described exemplifying embodiments thereof and thatother embodiments are conceivable within the scope of the followingClaims.

We claim:
 1. The use, in absorbent structures incorporated in absorbentarticles, such as diapers, sanitary napkins, tampons, panty protectors,incontinence guards, bed protectors, wound or sore dressings, salivaabsorbents and like articles, of a web dry-formed of particulatematerial containing 30-100% flash-dried cellulose fibres to a web with aweight per unit area of 100-2000 g/m², compressed to a density of0.3-1.0 g/cm³, and mechanically softened and delaminated beforeincorporation as the absorbent structure without any subsequentdefibration and fluffing.
 2. A method for manufacturing an absorbentstructure in an absorbent article, comprising:flash drying paper pulpinto flash-dried cellulose fibers, dry-forming particulate material to aweb with a weight per unit area of between 100-2000 g/m², 30-100% of theparticulate material including the flash-dried cellulose fibers,compressing said web to a web density of between 0.3-1.0 g/cm³,mechanically softening and delaminating the web, and incorporating saidmechanically softened and delaminated web as an absorbent structure inan absorbent article without subsequent defibration and fluffing.
 3. Themethod for manufacturing an absorbent structure according to claim 2,comprising compressing said web to a web density of between 0.4-0.9g/cm³.
 4. The method for manufacturing an absorbent structure accordingto claim 2, wherein the step of softening and therewith delaminiatingsaid web before incorporating it as an absorbent structure in anabsorbent article achieves in said web a plurality of partiallyseparated thin fibre layers, which in themselves exhibit a density whichcorresponds to said web density.
 5. The method of claim 2, wherein theabsorbent article is a diaper, sanitary napkin, panty protector,incontinence guard, bed protector, a wound or sore dressing, or salivaabsorbent.
 6. An absorbent structure, wherein the structure has beenmanufactured according to the method claimed in claim
 2. 7. Theabsorbent structure according to claim 6, wherein the weight per unitarea of the structure is between 150-1500 g/m².
 8. The absorbentstructure according to claim 6, wherein said cellulose fibres are mainlycomprised of fibres of chemi-thermomechanically produced pulp.
 9. Theabsorbent structure according to claim 8, wherein saidchemi-thermomechanical pulp fibres have a curl value of between 0.20 and0.40.
 10. The absorbent structure according to claim 6, wherein saidcellulose fibre are mainly comprised of fibres of chemically producedpulp.
 11. The absorbent structure according to claim 6, wherein some ofsaid fibres are chemically stiffened cellulose fibres.
 12. The absorbentstructure according to claim 6, wherein the structure includes between20-70% superabsorbent material, calculated on the total weight of thestructure in a dry state.
 13. The absorbent structure according claim 6,wherein the structure includes reinforcing means.
 14. The absorbentstructure of claim 6, wherein the absorbent article is a diaper,sanitary napkin, panty protector, incontinence guard, bed protector, awound or sore dressing, or saliva absorbent.
 15. The absorbent structureof claim 13, wherein the reinforcing means is a binding agent,reinforcing fibers, or thermoplastic binding fibers.
 16. An absorbentarticle, comprising a liquid-permeable top sheet, an essentiallyliquid-impermeable bottom sheet, and an absorbent body which includes anabsorbent structure according to claim 6 enclosed between said sheets.17. The absorbent article according to claim 16, wherein said absorbentbody includes at least two layers, an acquisition layer and a secondlayer, said acquisition layer includes means for taking up fluid anddelivering the fluid to said second layer, said acquisition layerincluding the absorbent structure having a weight per unit area ofbetween 100-1500 g/m² and a density of between 0.3-1/0 g/cm³, whereinsaid second layer is one of a wicking layer and a storage layer.
 18. Theabsorbent article according to claim 17, wherein said wicking layerincludes between 0-40% superabsorbent material calculated on the totalweight of the structure in a dry state.
 19. An absorbent articleaccording to claim 16, wherein said absorbent body includes two layers,an acquisition layer and a storage layer wherein said acquisition layerincludes means for quickly taking up fluid and delivering the fluid tosaid storage layer, said storage layer comprising the absorbentstructure having a weight per unit area of between 100-2000 g/m² and adensity of between 0.4-1.0 g/cm³.
 20. The absorbent article according toclaim 19, wherein said storage layer includes between 20-70%superabsorbent material calculated on the total weight of said structurein a dry state.
 21. The absorbent article of claim 16, wherein theabsorbent article is a diaper, sanitary napkin, panty protector,incontinence guard, bed protector, a wound or sore dressing, or salivaabsorbent.